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What is Plunk?
Open-source email platform consolidating transactional emails, marketing campaigns, and workflow automation into one system. Self-hostable under AGPL-3.0 license, or use the managed cloud hosted in EU (GDPR compliant). Founded 2022 with 5000+ GitHub stars.
Plunk news
Plunk featured as top open-source email API for developers in 2026
Ranked among 7 best email APIs after SendGrid retired permanent free plan. Positioned as alternative for developers prioritizing open-source, cost-efficiency, and developer experience.
Source: Medium ↗Plunk receives trial review and developer platform analysis
PowerMTA Providers published detailed review noting Plunk's 5000+ GitHub stars, EU headquarters, and positioning for developers wanting open-source email with optional managed hosting.
Source: PowerMTA Providers ↗
Key features
Transactional Emails
Send emails via REST API or SMTP with template support, variable substitution, and attachments (up to 10 per email, 10MB total)
Workflow Automation
Event-triggered sequences with delays, conditions, and branching logic; basic automation without deep multi-step funnels
Campaign Broadcasts
Send newsletters and product updates to full list or targeted segments
Dynamic Segments
Real-time audience segmentation based on contact behavior, attributes, and engagement data
Inbound Email
Receive and process incoming emails on your domain via webhooks with custom routing rules
Email Scheduling & Throttling
Schedule emails up to 30 days ahead (cancel/move before send), throttle to send at most once per period
Analytics & Tracking
Real-time metrics on opens, clicks, bounces, unsubscribes, and engagement
Custom Domains
Send from your own domain with DKIM, SPF, and DMARC configured automatically
Email Validation
Catch typos, disposable domains, and missing MX records before sending
Plunk pricing
Plunk's pricing model charges only per email sent with no contact limits, undercutting competitors: Plunk $0.001/email vs Mailgun $0.003, SendGrid $0.002, Mailchimp $0.004. Free tier covers small teams; self-hosting is free.
| Plan | Price | What's included |
|---|---|---|
| Free Forever | $0 | 1,000 emails/month, transactional emails, workflow automation, campaign broadcasts, inbound email, email validation, custom domains, tracking, unlimited contacts (with Plunk branding) |
| Pay as You Grow | $0.001 per email | Everything in Free plus: no Plunk branding, monthly spend cap, unlimited emails |
| Self-Hosted | Free | Unlimited emails (infrastructure costs only), full data ownership, GDPR compliant by default |
Pros & cons
Pros
- + Open-source under AGPL-3.0 with self-hosting option for full data control
- + Transparent pricing at $0.001/email with no contact limits or feature tiers
- + All features included on every plan (no upsells or tiered capabilities)
- + Developer-friendly with REST API, SMTP, and official SDKs (Node.js, Python)
- + Combines transactional, workflow, and campaign email in single platform
- + EU-hosted and GDPR compliant by default
- + Quick setup (under 5 minutes with domain configuration)
- + Scheduling and throttling built into API (no external jobs needed)
Cons
- − Relatively new platform with smaller user base and community support
- − Free plan includes Plunk branding in emails
- − Automation capabilities more basic than competitors (no visual multi-step branching like ActiveCampaign)
- − Smaller ecosystem compared to SendGrid/Mailgun (fewer integrations, less community content)
Who is Plunk best for?
- • Developers and technical founders building SaaS applications
- • Startups with tight budgets needing transactional + marketing email
- • Teams that value open-source code ownership and transparency
- • Privacy-conscious deployments requiring self-hosting on own infrastructure
- • Applications needing inbound email handling alongside outbound sending
- • Companies sending 10K–100K emails/month where volume pricing beats fixed plans
Frequently asked questions
Can I schedule emails with Plunk?
Yes, schedule up to 30 days ahead using delivery.at with ISO 8601 timestamp. Move or cancel scheduled emails by ID until they send.
What is throttling and how does it work?
Throttling sends a notification at most once per period (e.g., daily usage warning). Add delivery.throttle to the API call; Plunk skips duplicate sends within the window without billing.
Does Plunk have contact limits?
No. Store unlimited contacts at no extra cost. You only pay per email sent.
Can I self-host Plunk?
Yes. Deploy with Docker Compose on your own infrastructure. AGPL-3.0 license allows full source code inspection and modification.
What languages does Plunk support?
REST API works from any language. Official SDKs available for Node.js and Python. SMTP support for existing tools.
Is Plunk GDPR compliant?
Yes. EU-hosted platform is GDPR compliant by default. Self-hosting gives full data control.
